This invention relates to ink jet print heads in which printing is effected by selective ejection of droplets of ink and in particular to such ink jet print heads constructed utilising nano-technology engineering.
Ink jet print heads are well known and include a nozzle to which ink in a liquid state is fed from an ink reservoir and droplets of the ink are selectively ejected under the control of electrical signals from the nozzle onto an ink receiving surface. Ejection of an ink droplet forms a dot on the ink receiving surface and ejection of the droplets is so controlled as to build up, dot-by-dot, a required printed image on the ink receiving surface. Ejection of ink droplets may be effected by various known means. For example electrical energisation of a diaphragm of piezo-electric material may be utilised to create a pulse of pressure in the ink adjacent the nozzle to cause ejection of a droplet of ink. In an alternative method, heat is applied to the ink to create bubbles in the ink adjacent the nozzle and the resultant increase in pressure ejects a droplet of ink. The nozzle is spaced from the ink receiving surface and the ink droplet is ejected with sufficient velocity to cause it to traverse the space between the nozzle and the ink receiving surface. Generally a print head is provided with a plurality of nozzles arranged in a line and the print head is traversed, in a direction perpendicular to the line of nozzles, across the print receiving surface to enable a line of characters to be printed in dot matrix form on the print receiving surface for each traverse of the print head.